Stable liquid formulations of melphalan

ABSTRACT

The present invention relates to stable, liquid parenteral formulations of Melphalan or pharmaceutically acceptable salts thereof. Further this invention also describes process of preparing such formulations.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase filing under 35 U.S.C. § 371of International Application PCT/IB2016/053881, filed Jun. 29, 2016, andpublished as WO 2017/002030 A1 on Jan. 5, 2017. PCT/IB2016/053881 claimspriority from Indian application number 3328/CHE/2015, filed Jun. 30,2015. The entire contents of each of these applications are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

Melphalan, also known as L-phenylalanine mustard, L-PAM, or L-sarcolysinis a phenylalanine derivative of nitrogen mustard. Melphalan is abifunctional alkylating agent that is active against selected humanneoplastic diseases. The molecular formula is C₁₃H₁₈C₁₂N₂O₂ and themolecular weight is 305.20. The structural formula is:

U.S. Pat. No. 4,997,651 to Stephen et al., discloses two-componentpharmaceutical formulation of Melphalan comprising freeze-driedMelphalan hydrochloride and a solvent-diluent comprising a citrate,propylene glycol and ethanol.

U.S patent application No. 2013/0131174 to Castillo et al., discloses asolid lyophilized composition of Melphalan hydrochloride having a pHbetween 4 and 6.

U.S patent application Nos. 2010/0311838, 2014/0213650 and 2014/0221488disclose parenteral compositions comprising Melphalan and a cyclodextrinderivative.

RU2060031 discloses parenteral lyophilized formulation comprising aMelphalan, polyvinylpyrrolidone, ascorbic acid, glutamic acid,hydrochloric acid and D-mannitol.

The commercial formulation of injectable Alkeran® consists of twocomponents comprising of Melphalan hydrochloride andpolyvinylpyrrolidone lyophilized and a diluent comprising a mixture ofsodium citrate, water for injection, propylene glycol and ethanol.

The Alkeran® to be infused must be diluted to not more than 0.45 mg/mlin normal saline and infused over 15 minutes.

The reconstitution of the lyophilized product is clinically inconvenientand the lyophilization process is time consuming and often incurssignificant expense. Hence, there is a strong need to develop alternateformulations of Melphalan.

The inventors have developed ready to use liquid formulation ofMelphalan which overcomes the disadvantages of the formulations reportedin prior art.

SUMMARY OF THE INVENTION

One object of the invention provides ready to use liquid parenteralformulation of Melphalan.

Another aspect of the present invention is to provide ready to useliquid parenteral formulation comprising Melphalan, one or moresolvents, anti-oxidants and other pharmaceutically acceptable adjuvantsthereof.

Yet another aspect of the present invention provides method forpreparing ready to use liquid parenteral formulation of Melphalancomprising Melphalan Hydrochloride, one or more solvents, anti-oxidantsand other pharmaceutically acceptable adjuvants thereof.

DETAILED DESCRIPTION OF THE INVENTION

In the context of this invention “Melphalan” refers to thepharmaceutically acceptable salts, solvates, hydrates and anhydrousforms thereof, preferably Melphalan Hydrochloride.

As used herein, “ready to use” Melphalan formulations refers toformulations that contain Melphalan in dissolved or solubilized form andare intended to be used as such or upon further dilution in intravenousdiluents.

In one embodiment, ready to use liquid parenteral formulations ofMelphalan comprise

i. Melphalan,

ii. one or more solvents,

iii. anti-oxidants,

optionally other pharmaceutically acceptable adjuvants thereof.

In yet another embodiment, ready to use liquid parenteral formulationsof Melphalan comprise

-   -   i. Melphalan Hydrochloride,    -   ii. one or more solvents selected from the group comprising of        dimethylacetamide, polyethylene glycol, ethanol, propylene        glycol and glycerine,    -   iii. anti-oxidants selected from monothioglycerol, L-cysteine,        ascorbic acid and optionally other pharmaceutically acceptable        adjuvants thereof.

The composition according to the present invention is intended to bestored at a temperature of 2-8° C.

Suitable solvents include, but are not limited to dimethylacetamide(DMA), dimethyl sulfoxide (DMSO), N-methylpyrrolidone,dimethylisosorbide, ethanol, propylene glycol, glycerine, polyethylenealcohol, propylene glycol esters, polyethylene glycols and the like.Preferred solvents are dimethylacetamide (DMA), ethanol, polyethyleneglycols (PEG), glycerine and propylene glycol.

The pharmaceutical compositions of the present invention also containone or more anti-oxidants selected from the group, but not limited tobutylated hydroxyanisole (BHA), butylated hydroxyl toluene (BHT), citricacid, lactic acid, benzoic acid, tocopherol (Vitamin E),ethylenediaminetetraacetic acid, sodium metabisulfite, sodium bisulfite,monothioglycerol, ascorbic acid and their esters, L-cysteine, parabens,benzyl alcohol, propyl gallate, thioglycolic acid, tartaric acid,phosphoric acid, gluconic acid, thiodipropionic acid, acetonicdicarboxylic acid, amino acids such as histidine, cysteine, tryptophan,tyrosine; chelating agents and the like. Most preferred anti-oxidant ismonothioglycerol.

The formulation of the present invention may additionally containbuffers, pH adjusting agents, stabilizers such as, but not limited tocitrate buffer, glutamate, dicarboxylic acid, lecithin,di(hydroxyethyl)glycine, sorbitol, bicarbonate, tartrate, benzoate,lactate, gluconate, glycine, TRIS buffer, acetate buffer, boric acidbuffer, phosphate buffer, amino acids, meglumine and the like.

Solubility studies were carried out with various solvents at 25° C.temperature, to check the solubility of Melphalan hydrochloride. Thedata is summarized in table 1:

TABLE 1 Solubility studies in various solvents Quantity of solvents Qtyof Melphalan PEG- Propylene Hydrochloride DMA 400 Glycol Ethanol Result100 mg 1.1 mL — — — Clear 100 mg 0.5 mL — —  0.5 mL Clear 100 mg — —   1mL — Not Clear 100 mg — — —   1 mL Hazy solution 100 mg 0.3 mL — 0.05mL  0.65 mL Clear 100 mg — 1.0 mL   0 mL — Clear after vigorous mixing100 mg — 0.9 mL 0.1 mL — Clear 100 mg — 0.7 mL 0.3 mL — Clear 100 mg —0.5 mL 0.5 mL — Clear 100 mg — 0.2 mL 0.8 mL — Clear 100 mg — 0.1 mL 0.9mL — Clear

In one of the preferred embodiment, ready to use liquid parenteralformulations of Melphalan comprise:

i. Melphalan Hydrochloride 1 to 30% ii. dimethylacetamide orpolyethylene glycol 20 to 95% iii. ethanol 0 to 50% iv. propyleneglycol. 5 to 50% v. monothioglycerol 0.05 to 5%by weight of the composition.

The invention further relates to a process of preparing liquidformulations of Melphalan. The process comprises:

-   -   i. Addition of Melphalan to the manufacturing vessel containing        solvent and stirred till a clear solution is obtained.    -   ii. Addition of remaining solvents to the above solution and        stirred.    -   iii. Addition of anti-oxidant to the solution and stirred till a        homogenous solution is obtained.    -   iv. Filtering and filling the solution in to suitable containers        or vials.

Melphalan formulation prepared according to the invention was tested forstability at various stability conditions such as 2-8° C. and 25° C./60%RH for a period of 6 months. Stability data is summarized in table 2.

TABLE 2 Stability data for the product obtained from Example 5 Condition2-8° C. 25° C./60% RH Time point Initial 1 M 3 M 6 M 1 M 3 M 6 M AssayBy HPLC (%) 99.2 97.8 97.7 96.8 97.2 94.0 90.1 Total Impurities 0.170.24 0.32 0.75 0.89 2.26 4.33 (% w/w)

Surprisingly no significant increase in total impurities was observedeven at 25° C./65% RH. The inventors have found that liquidpharmaceutical formulation of Melphalan comprising of one or moresolvents selected form DMA, Ethanol, PEG and propylene glycol in thepresence of an anti-oxidant yields a stable liquid formulation ofMelphalan overcoming the disadvantages associated with prior art.

Comparative dilution studies were performed to check the stability ofthe diluted formulations. Melphalan formulation prepared according tothe invention was diluted with 0.9% NaCl to get concentration of 0.45mg/mL. Alkeran® vial (Batch No: P283) was considered as reference forcomparative dilution study. Stability of the diluted product was studiedat 0 minutes, 30 mins and 60 min. The stability data of the inventionformulation and reference product is summarized in table 3.

TABLE 3 Comparative dilution study of the invention formulation withreference product Dilution study with 0.9% NaCl Formulation Referenceproduct Invention formulation after reconstitution with after dilutionwith diluent, followed by 0.9% NaCl dilution with 0.9% NaCl Time pointInitial 30 min 60 min Initial 30 min 60 min Assay (%) 97.3 97.6 95.295.6 91.1 88.2 pH of Solution 3.51 3.48 3.48 5.83 6.06 6.35 Osmolality352 348 354 1120 1119 1122 (mOsm/kg) Related Substances Impurities %(w/w) Impurity D 1.23 3.31 5.35 1.11 3.67 5.73 Impurity G 0.14 0.15 0.170.49 0.52 0.51 Total 1.6 3.8 5.8 1.94 5.08 7.65 Impurities

Surprisingly Melphalan formulation prepared according to the inventionshowed better stability profile compared to the reference product.

The following examples further describe certain specific aspects andembodiments of the present invention and demonstrate the practice andadvantages thereof.

Example 1

Qty/vial Ingredients (mg) Melphalan Hydrochloride  20-200 N,N,Dimethylacetamide 350-490 Ethanol 200-280 Propylene glycol 180-270Monothioglycerol 3-8

Manufacturing Process

Melphalan Hydrochloride was added to the manufacturing vessel containingN, N, Dimethyl acetamide and ethanol and stirred to get a clearsolution. Propylene glycol was added, followed by the addition ofmonothioglycerol and stirred to get homogenous solution. The obtainedsolution was filtered and filled in vials followed by capping andsealing.

Melphalan formulation prepared according to the invention was tested forstability at various stability conditions such as 2-8° C. and 25° C./60%RH for a period of 6 months. Stability data is summarized in table 4.

TABLE 4 Stability data for the product obtained from Example 1 Condition2-8° C. 25° C. Time point Initial 1 M 3 M 6 M 1 M 3 M 6 M Assay By 100.3100.3 103.3 98.3 99.5 101.1 94.4 HPLC (%) Total 0.19 0.16 0.20 0.63 0.301.60 4.37 impurities *RRT: Relative Retention Time

Example 2

Qty/vial Qty/vial Qty/vial Ingredients (mg) (mg) (mg) Melphalan 20-20020-200 20-200 Hydrochloride N, N, Dimethyl 380 380 380 acetamide Ethanol240 320 280 Propylene glycol 310 210 260 Monothioglycerol 2.53 5.05 5.05

Manufacturing Process

Melphalan Hydrochloride was added to the manufacturing vessel containingN,N,dimethyl acetamide and ethanol and stirred to get a clear solution.Propylene glycol was added, followed by the addition of monothioglyceroland stirred to get homogenous solution. The obtained solution wasfiltered and filled in vials followed by capping and sealing.

Example 3

Qty/vial Ingredients (mg) Melphalan Hydrochloride 20-200 Polyethyleneglycol 570 Ethanol 240 Propylene glycol 210 Monothioglycerol 5.05

Manufacturing Process

Melphalan Hydrochloride was added to the manufacturing vessel containingpolyethylene glycol and ethanol and stirred to get a clear solution.Propylene glycol was added, followed by the addition of monothioglyceroland stirred to get homogenous solution. The obtained solution wasfiltered and filled in vials followed by capping and sealing.

Example 4

Quantity/vial Ingredients (mg) Melphalan Hydrochloride  20-200Polyethylene glycol-400 490-620 Propylene glycol 320-390Monothioglycerol 5.05

Manufacturing Process

Melphalan Hydrochloride was added to the manufacturing vessel containingpolyethylene glycol. Propylene glycol was added, followed by theaddition of monothioglycerol and stirred to get homogenous solution. Theobtained solution was filtered and filled in vials followed by cappingand sealing.

Example 5

Quantity/vial Ingredients (mg) Melphalan Hydrochloride  20-200Polyethylene glycol-400 590-950 Propylene glycol 120-420Monothioglycerol 5-8

Manufacturing Process

Melphalan Hydrochloride was added to the manufacturing vessel containingpolyethylene glycol. Propylene glycol was added, followed by theaddition of monothioglycerol and stirred to get homogenous solution. Theobtained solution was filtered and filled in vials followed by cappingand sealing.

1. (canceled) 2: The formulation of claim 3, wherein the pH of theformulation is between 2 to
 5. 3: A stable, liquid parenteralformulation consisting essentially of: (i) Melphalan (ii) one or moresolvents and (iii) one or more anti-oxidants. 4: A stable, liquidparenteral formulation consisting essentially of: (i) Melphalanhydrochloride (ii) one or more solvents selected from dimethylacetamide, polyethylene glycol, ethanol, propylene glycol and glycerine.(iii) anti-oxidants selected from monothioglycerol, L-cysteine andchelating agents.
 5. (canceled) 6: The stable, liquid parenteralformulation of claim 4 consisting of: (i) Melphalan hydrochloride 1 to30% (ii) dimethylacetamide 20 to 85% (iii) ethanol 0 to 50% (iv)propylene glycol 5 to 50% (v) at least one of monothioglycerol,chelating agent, 0.05 to 5% and both in combination by weight of thecomposi- tion.

7: The stable, liquid parenteral formulation of claim 4 consisting of:(i) Melphalan hydrochloride 1 to 30% (ii) polyethylene glycol 20 to 85%(iii) ethanol 0 to 50% (iv) propylene glycol 5 to 50% (v) at least oneof monothioglycerol, chelating agent, 0.05 to 5% and both in combinationby weight of the composi- tion.

8: A stable, liquid parenteral formulation of Melphalan consistingessentially of: (i) Melphalan hydrochloride 1 to 30% (ii) polyethyleneglycol 20 to 85% (iii) propylene glycol 5 to 50% (iv) monothioglycerol0.05 to 5% (v) chelating agent by weight of the composition. 0.01 to 5%